A Programmable current source for magnetic resonance current density imaging (MRCDI) at 3 tesla

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2014

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Göksu, Cihan

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Electrical properties of biological tissues are distinctive between various types of the tissues, and significantly related with the pathological conditions of the tissues. For instance, conductivity images can be used for tumor identification. Besides, current density distribution may provide useful information in research and development of electrical stimulation, electro-surgery, defibrillation, and cardiac pacing devices. Magnetic resonance current density imaging (MRCDI) and magnetic resonance electrical impedance tomography (MREIT) are two imaging modalities based on the current density distribution and the conductivity variation in biological tissues. In this thesis, a four-channel programmable current source to be used in MRCDI and MREIT applications, is designed and implemented. The current source is composed of a microcontroller unit (MCU), a digital to analog converter (DAC), a step-up DC-DC converter, and a voltage to current (V-I) converter with a current steering topology. Two different MRCDI experiments are performed in this study. In the first experiment, the current density distribution inside a uniform phantom is investigated. In the second experiment, a current steering insulating layer is inserted inside the uniform phantom, and the current density distribution is investigated. In order to check the accuracy of the experiments, the total injected current is compared with the total integrated current, which is calculated from reconstructed current density images. It is concluded that, the experiments are performed with 7.4% error. Keywords: Magnetic resonance, current density imaging, programmable current source, microcontroller unit, step-up DC-DC converter.

Subject Keywords

Magnetic resonance imaging., Electrical impedance tomography., Electric conductivity., DC-to-DC converters.

URI

http://etd.lib.metu.edu.tr/upload/12616873/index.pdf
https://hdl.handle.net/11511/23323

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

C. Göksu, “A Programmable current source for magnetic resonance current density imaging (MRCDI) at 3 tesla,” M.S. - Master of Science, Middle East Technical University, 2014.